Selection guidelines for different capping devices under various operating conditions are listed in table 1. However, these guidelines cannot substitute for testing a shield or seal in its application. For additional information, refer to Sealing solutions.

The seals, which are fitted in a recess on the outer ring, make good, positive contact with the recess, without deforming the outer ring. The capping devices are available as:

RS1 seals are made of sheet steel reinforced NBR and seal against the inner ring shoulder or against a recess in the inner ring side face (fig. 5).

Bearings with designation suffix VP311 are equipped with seals made of food compatible, blue-coloured NBR.
The material is FDA and EC approved. FDA approval is based on compliance with CFR 21 section 177.2600 'Rubber articles intended for repeated use' for use in contact with aqueous and fatty foods. EC approval is based on compliance with the overall migration requirements of the German BfR recommendation XXI for category 3 materials.

RS2 seals are similar to RS1 seals, but are made of sheet steel reinforced FKM.

WARNING

Seals made of PTFE (polytetrafluoroethylene) or FKM (fluoro rubber) exposed to an open flame or temperatures above 300 °C (570 °F) are a health and environmental hazard! They remain dangerous even after they have cooled.

The NSF registration confirms the grease fulfils the requirements listed in the US Food and Drug Administration's guidlines under 21 CFR section 178.3570 (lubricant acceptable with incidental food contact for use in and around food processing areas).

available on request: special non-toxic grease, registered by NSF as category H1 (designation suffix VT378)

The technical specifications of the various greases are listed in table 2.

Grease life for capped bearings

is presented as L10, i.e. the time period at the end of which 90% of the bearings are still reliably lubricated (diagram 1)

When capped bearings must operate under certain extreme conditions, such as very high speeds or high temperatures, grease may appear on the capping diameter. For bearing arrangements where this would be detrimental, appropriate actions could be taken. For additional information, contact the SKF application engineering service.

Depending on their design, series and size, SKF stainless steel deep groove ball bearings are fitted with one of the cages shown in table 4. The standard stamped stainless steel cage is not identified in the bearing designation. If non-standard cages are required, check availability prior to ordering.

When used at high temperatures, some lubricants can have a detrimental effect on polyamide cages. For additional information about the suitability of cages, refer to Cages and Cage materials.